cheapo fire wood brick, lay a temp on it and start sawing, then rasp it.. alot, then sand it... alot, then cut out the part where the grip needs to be attached and well... there ya have your own stock for the some of... free?? My wood was a scrap piece... so my stock cost no nothing nulla... and is actually the only part, together with the alu grip that lasts
I used a piece of popular on my ESB stock. Turned out nice. Popular is one of the softest hardwoods you can find. It doesn't look like an old piece of pine if finished correctly. And by it being soft...I cut mine in the general shape and then used a belt sander to finish roughing out the curves and whatnot.
I didn't have a good way of routing this material, so what I did was make mine from two pieces of wood. The one side was the poplular board, the other side where the stock connector goes was 3/8" plywood. This way all I had to do was cut the shape of the stock and the hole out of the 3/8" piece. When that was done, I glued the 2 pieces together. I used some wood filler to fill any gaps and sanded the pieces until they were smooth together.
When I was putting the finish on my stock, I used a varnish with stain already in it - Dark walnut I believe. After each coat of varnish, I dusted it with flat black spray paint along the edges. I did this about 3 times and finished with a last coast of varnish. It really gave it an aged, weathered look and helped hide the seam between the 2 pcs, because you can't see the grain change due to the dark color.